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package pgproto3
import (
"encoding/binary"
"errors"
"fmt"
"io"
)
// Frontend acts as a client for the PostgreSQL wire protocol version 3.
type Frontend struct {
cr ChunkReader
w io.Writer
// Backend message flyweights
authenticationOk AuthenticationOk
authenticationCleartextPassword AuthenticationCleartextPassword
authenticationMD5Password AuthenticationMD5Password
authenticationGSS AuthenticationGSS
authenticationGSSContinue AuthenticationGSSContinue
authenticationSASL AuthenticationSASL
authenticationSASLContinue AuthenticationSASLContinue
authenticationSASLFinal AuthenticationSASLFinal
backendKeyData BackendKeyData
bindComplete BindComplete
closeComplete CloseComplete
commandComplete CommandComplete
copyBothResponse CopyBothResponse
copyData CopyData
copyInResponse CopyInResponse
copyOutResponse CopyOutResponse
copyDone CopyDone
dataRow DataRow
emptyQueryResponse EmptyQueryResponse
errorResponse ErrorResponse
functionCallResponse FunctionCallResponse
noData NoData
noticeResponse NoticeResponse
notificationResponse NotificationResponse
parameterDescription ParameterDescription
parameterStatus ParameterStatus
parseComplete ParseComplete
readyForQuery ReadyForQuery
rowDescription RowDescription
portalSuspended PortalSuspended
bodyLen int
msgType byte
partialMsg bool
authType uint32
}
// NewFrontend creates a new Frontend.
func NewFrontend(cr ChunkReader, w io.Writer) *Frontend {
return &Frontend{cr: cr, w: w}
}
// Send sends a message to the backend.
func (f *Frontend) Send(msg FrontendMessage) error {
_, err := f.w.Write(msg.Encode(nil))
return err
}
func translateEOFtoErrUnexpectedEOF(err error) error {
if err == io.EOF {
return io.ErrUnexpectedEOF
}
return err
}
// Receive receives a message from the backend. The returned message is only valid until the next call to Receive.
func (f *Frontend) Receive() (BackendMessage, error) {
if !f.partialMsg {
header, err := f.cr.Next(5)
if err != nil {
return nil, translateEOFtoErrUnexpectedEOF(err)
}
f.msgType = header[0]
f.bodyLen = int(binary.BigEndian.Uint32(header[1:])) - 4
f.partialMsg = true
if f.bodyLen < 0 {
return nil, errors.New("invalid message with negative body length received")
}
}
msgBody, err := f.cr.Next(f.bodyLen)
if err != nil {
return nil, translateEOFtoErrUnexpectedEOF(err)
}
f.partialMsg = false
var msg BackendMessage
switch f.msgType {
case '1':
msg = &f.parseComplete
case '2':
msg = &f.bindComplete
case '3':
msg = &f.closeComplete
case 'A':
msg = &f.notificationResponse
case 'c':
msg = &f.copyDone
case 'C':
msg = &f.commandComplete
case 'd':
msg = &f.copyData
case 'D':
msg = &f.dataRow
case 'E':
msg = &f.errorResponse
case 'G':
msg = &f.copyInResponse
case 'H':
msg = &f.copyOutResponse
case 'I':
msg = &f.emptyQueryResponse
case 'K':
msg = &f.backendKeyData
case 'n':
msg = &f.noData
case 'N':
msg = &f.noticeResponse
case 'R':
var err error
msg, err = f.findAuthenticationMessageType(msgBody)
if err != nil {
return nil, err
}
case 's':
msg = &f.portalSuspended
case 'S':
msg = &f.parameterStatus
case 't':
msg = &f.parameterDescription
case 'T':
msg = &f.rowDescription
case 'V':
msg = &f.functionCallResponse
case 'W':
msg = &f.copyBothResponse
case 'Z':
msg = &f.readyForQuery
default:
return nil, fmt.Errorf("unknown message type: %c", f.msgType)
}
err = msg.Decode(msgBody)
return msg, err
}
// Authentication message type constants.
// See src/include/libpq/pqcomm.h for all
// constants.
const (
AuthTypeOk = 0
AuthTypeCleartextPassword = 3
AuthTypeMD5Password = 5
AuthTypeSCMCreds = 6
AuthTypeGSS = 7
AuthTypeGSSCont = 8
AuthTypeSSPI = 9
AuthTypeSASL = 10
AuthTypeSASLContinue = 11
AuthTypeSASLFinal = 12
)
func (f *Frontend) findAuthenticationMessageType(src []byte) (BackendMessage, error) {
if len(src) < 4 {
return nil, errors.New("authentication message too short")
}
f.authType = binary.BigEndian.Uint32(src[:4])
switch f.authType {
case AuthTypeOk:
return &f.authenticationOk, nil
case AuthTypeCleartextPassword:
return &f.authenticationCleartextPassword, nil
case AuthTypeMD5Password:
return &f.authenticationMD5Password, nil
case AuthTypeSCMCreds:
return nil, errors.New("AuthTypeSCMCreds is unimplemented")
case AuthTypeGSS:
return &f.authenticationGSS, nil
case AuthTypeGSSCont:
return &f.authenticationGSSContinue, nil
case AuthTypeSSPI:
return nil, errors.New("AuthTypeSSPI is unimplemented")
case AuthTypeSASL:
return &f.authenticationSASL, nil
case AuthTypeSASLContinue:
return &f.authenticationSASLContinue, nil
case AuthTypeSASLFinal:
return &f.authenticationSASLFinal, nil
default:
return nil, fmt.Errorf("unknown authentication type: %d", f.authType)
}
}
// GetAuthType returns the authType used in the current state of the frontend.
// See SetAuthType for more information.
func (f *Frontend) GetAuthType() uint32 {
return f.authType
}
|
